02663nas a2200229   4500008004100000022001400041245013900055210006900194260000900263300001400272490000800286520184200294100002802136700001602164700001902180700002202199700002102221700001902242700002202261700002002283856013002303       2021                        eng d  a0002-786300aHeterogeneous C-H functionalization in water via porous covalent organic framework nanofilms: a case of catalytic sphere transmutation0 aHeterogeneous CH functionalization in water via porous covalent   cJUN   a8426-84360 v1433 aHeterogeneous catalysis in water has not been explored beyond certain advantages such as recyclability and recovery of the catalysts from the reaction medium. Moreover, poor yield, extremely low selectivity, and active catalytic site deactivation further underrate the heterogeneous catalysis in water. Considering these facts, we have designed and synthesized solution-dispersible porous covalent organic framework (COF) nanospheres. We have used their distinctive morphology and dispersibility to functionalize unactivated C-H bonds of alkanes heterogeneously with high catalytic yield (42-99%) and enhanced regioand stereoselectivity (3 degrees:2 degrees = 105:1 for adamantane). Further, the fabrication of catalyst-immobilized COF nanofilms via covalent self-assembly of catalytic COF nanospheres for the first time has become the key toward converting the catalytically inactive homogeneous catalysts into active and effective heterogeneous catalysts operating in water. This unique covalent self-assembly occurs through the protrusion of the fibers at the interface of two nanospheres, transmuting the catalytic spheres into films without any leaching of catalyst molecules. The catalyst-immobilized porous COF nanofilms' chemical functionality and hydrophobic environment stabilize the high-valent transient active oxoiron(V) intermediate in water and restricts the active catalytic site's deactivation. These COF nanofilms functionalize the unactivated C-H bonds in water with a high catalytic yield (45-99%) and with a high degree of selectivity (cis:trans = 155:1; 3 degrees:2 degrees = 257:1, for cis-1,2-dimethylcyclohexane). To establish this approach's ``practical implementation'', we conducted the catalysis inflow (TON = 424 +/- 5) using catalyst-immobilized COF nanofilms fabricated on a macroporous polymeric support.1 aSasmal, Himadri, Sekhar1 aBag, Saikat1 aChandra, Bittu1 aMajumder, Poulami1 aKuiry, Himangshu1 aKarak, Suvendu1 aGupta, Sayam, Sen1 aBanerjee, Rahul  uhttps://library.ncl.res.in/content/heterogeneous-c-h-functionalization-water-porous-covalent-organic-framework-nanofilms-case02903nas a2200325   4500008004100000022001400041245010100055210006900156260000800225300001400233490000800247520183600255100001602091700002802107700002802135700001702163700002102180700002202201700002002223700002002243700001902263700001902282700003302301700003202334700002502366700001802391700001702409700002002426856013102446       2023                        eng d  a0002-786300aCovalent organic framework thin-film photodetectors from solution-processable porous nanospheres0 aCovalent organic framework thinfilm photodetectors from solution  cJAN  a1649-16590 v1453 a<p>
	The synthesis of homogeneous covalent organic framework (COF) thin films on a desired substrate with decent crystallinity, porosity, and uniform thickness has great potential for optoelectronic applications. We have used a solution-processable sphere transmutation process to synthesize 300 +/- 20 nm uniform COF thin films on a 2 x 2 cm2 TiO2-coated fluorine-doped tin oxide (FTO) surface. This process controls the nucleation of COF crystallites and molecular morphology that helps the nanospheres to arrange periodically to form homogeneous COF thin films. We have synthesized four COF thin films (TpDPP, TpEtBt, TpTab, and TpTta) with different functional backbones. In a close agreement between the experiment and density functional theory, the TpEtBr COF film showed the lowest optical band gap (2.26 eV) and highest excited-state lifetime (8.52 ns) among all four COF films. Hence, the TpEtBr COF film can participate in efficient charge generation and separation. We constructed optoelectronic devices having a glass/FTO/TiO2/COF-film/Au architecture, which serves as a model system to study the optoelectronic charge transport properties of COF thin films under dark and illuminated conditions. Visible light with a calibrated intensity of 100 mW cm-2 was used for the excitation of COF thin films. All of the COF thin films exhibit significant photocurrent after illumination with visible light in comparison to the dark. Hence, all of the COF films behave as good photoactive substrates with minimal pinhole defects. The fabricated out-of-plane photodetector device based on the TpEtBr COF thin film exhibits high photocurrent density (2.65 +/- 0.24 mA cm-2 at 0.5 V) and hole mobility (8.15 +/- 0.64 x10-3 cm2 V-1 S-1) compared to other as synthesized films, indicating the best photoactive characteristics.</p>
1 aBag, Saikat1 aSasmal, Himadri, Sekhar1 aChaudhary, Sonu, Pratap1 aDey, Kaushik1 aBlaette, Dominic1 aGuntermann, Roman1 aZhang, Yingying1 aPoloz, Miroslav1 aKuc, Agnieszka1 aShelke, Ankita1 aVijayaraghavan, Ratheesh, K.1 aAjithkumar, Thalasseril, G.1 aBhattacharyya, Sayan1 aHeine, Thomas1 aBein, Thomas1 aBanerjee, Rahul  uhttps://library.ncl.res.in/content/covalent-organic-framework-thin-film-photodetectors-solution-processable-porous-nanospheres02677nas a2200265   4500008004100000022001400041245008300055210006900138260000900207300001400216490000700230520184900237100001902086700001602105700001702121700002502138700001602163700001702179700001602196700001902212700002602231700002002257700002002277856011402297       2023                        eng d  a2041-652000aHierarchical covalent organic framework-foam for multi-enzyme tandem catalysis0 aHierarchical covalent organic frameworkfoam for multienzyme tand  cJUN   a6643-66530 v143 a<p>
	Covalent organic frameworks (COFs) are ideal host matrices for biomolecule immobilization and biocatalysis due to their high porosity, various functionalities, and structural robustness. However, the porosity of COFs is limited to the micropore dimension, which restricts the immobilization of enzymes with large volumes and obstructs substrate flow during enzyme catalysis. A hierarchical 3D nanostructure possessing micro-, meso-, and macroporosity could be a beneficial host matrix for such enzyme catalysis. In this study, we employed an in situ CO2 gas effervescence technique to induce disordered macropores in the ordered 2D COF nanostructure, synthesizing hierarchical TpAzo COF-foam. The resulting TpAzo foam matrix facilitates the immobilization of multiple enzymes with higher immobilization efficiency (approximately 1.5 to 4-fold) than the COF. The immobilized cellulolytic enzymes, namely beta-glucosidase (BGL), cellobiohydrolase (CBH), and endoglucanase (EG), remain active inside the TpAzo foam. The immobilized BGL exhibited activity in organic solvents and stability at room temperature (25 degrees C). The enzyme-immobilized TpAzo foam exhibited significant activity towards the hydrolysis of p-nitrophenyl-beta-d-glucopyranoside (BGL@TpAzo-foam: K-m and V-max = 23.5 +/- 3.5 mM and 497.7 +/- 28.0 mu M min(-1)) and carboxymethylcellulose (CBH@TpAzo-foam: K-m and V-max = 18.3 +/- 4.0 mg mL(-1) and 85.2 +/- 9.6 mu M min(-1) and EG@TpAzo-foam: K-m and V-max = 13.2 +/- 2.0 mg mL(-1) and 102.2 +/- 7.1 mu M min(-1)). Subsequently, the multi-enzyme immobilized TpAzo foams were utilized to perform a one-pot tandem conversion from carboxymethylcellulose (CMC) to glucose with high recyclability (10 cycles). This work opens up the possibility of synthesizing enzymes immobilized in TpAzo foam for tandem catalysis.</p>
1 aPaul, Satyadip1 aGupta, Mani1 aDey, Kaushik1 aMahato, Ashok, Kumar1 aBag, Saikat1 aTorris, Arun1 aGowd, Bhoje1 aSajid, Hasnain1 aAddicoat, Matthew, A.1 aDatta, Supratim1 aBanerjee, Rahul  uhttps://library.ncl.res.in/content/hierarchical-covalent-organic-framework-foam-multi-enzyme-tandem-catalysis